A pillow packaging apparatus, one type of a packaging apparatus has the following configuration. The pillow packaging apparatus continuously supplies a belt-like film wound around an original film roll into a bag-making device where the belt-like film undergoes to bag-making process. Furthermore, a center sealing device arranged downstream of the bag-making device seals the overlapping edges of the bag-shaped (i.e., tubular) film having undergone the bag-making process. As a result, a tubular film is obtained. In addition, a transporting and feeding device is arranged upstream of the bag-making device, and is configured to supply a product having been transported at a predetermined interval from the transporting and feeding device into the bag-making device. Due to the afore-mentioned configuration, upon passing the bag-making device, the product is received within the tubular film at a predetermined interval, and transported together with the tubular film. A top sealing device which is arranged adjacent to an outlet of the pillow packaging apparatus cuts and seals the tubular film such that the tubular film is laterally traversed at a predetermined interval, thereby obtaining a packaged body in which the product is enclosed or contained.
However, in a case where the product to be packaged is, for example, a food such as a steamed bread or a sweet, in terms of good keeping the packaged body may be filled with inert gas. FIG. 1 shows an exemplary packaging apparatus having a function of filling inert gas. The packaging apparatus as shown in FIG. 1 is a pillow packaging apparatus, and is provided with a gas nozzle 3 for ejecting gas into a tubular film 2, the shape of which is formed by a bag-making device 1. The gas nozzle 3 is inserted into the tubular film 2. A tip or front end portion of the gas nozzle 3 is disposed adjacent to a top sealing device 4, which seals and cuts the tubular film 2. Furthermore, a rear end portion of the gas nozzle 3 is connected to a gas generating device 5. Inert gas generated by the gas generating device 5 is ejected and supplied into the tubular film 2 through the gas nozzle 3.
As such, air existing inside the front end portion of the tubular film 2 adjacent to the top sealing device 4 is pushed out upstream of the tubular film 2, and is replaced with the inert gas ejected through the gas nozzle 3. The tubular film 2 is sealed and cut by the top sealing device 4 with the front end portion of the tubular film 2 filled with the inert gas. As a result, a packaged body 6 filled with the inert gas therein is produced. The afore-mentioned packaging apparatus is disclosed in, for example, Patent Document 1.